PVPower: The company develops software for solar panel installers to run their businesses, such as designing solar-panel systems and managing their inventory of equipment.

FORBES: A Guide To Building A Successful Green Tech Company

It's almost stock Android 2.2, by the looks of it, but eFun opted to take the familiar Android soft keys into software, leaving the only capacitive touch for the panel.

ENGADGET: eFun Nextbook Next4 and Next6 hands-on Hands-on

Users can intuitively operate the calculator using the stylus on the touch-panel LCD, and input data using the software keyboard.

ENGADGET: Casio's touchscreen graphing calculator arrives in 2013, makes the TI-84+ look dated